The Study On Tool Wear And Residual Stress In Milling Titanium Alloys

Titanium alloy(Ti-6Al-4V)is widely used in aviation,aerospace,nuclear energy and biomedical industry because of its excellent mechanical properties.However,the severe tool wear,poor surface quality and low machining efficiency during cutting process have become main factors that restrict its development.In particular,the emergence of the additive manufacturing technology results in material property changes.Research on tool wear morphology,wear mechanisms during milling process and using a reasonable wear rate calculation method to predict tool wear is of great significance for tool life assessment.In addition,worn tools have a great influence on the extent and the distribution of residual stress at the workpiece surface.It is important to predict the residual stress distribution to improve process efficiency and optimize process parameters during the machining process.In this study,slot milling experiments with large material removal parameters of rolled and AMed titanium alloy parts are carried out to analyse the wear mophorlogy.A thermo-mechanically-coupled tool wear model,consisting of abaration,adhesion and diffusion mechanisms,is implemented in the Simulink software to predict the flank wear length,which is verified by end milling experiments with rolled titanium alloy parts.A two-dimensional model of variable cutting thickness is established by simplifying the actual milling process.The extent and the distribution of residual stress on the surface and subsurface of workpiece are predicted by Deform 2D Finite Element software.Flank milling experiments of rolled and AMed titanium alloy parts are performed to verify the finite element simulation results.By comparing and analyzing variable cutting thickness model and equal cutting thickness model,the mechanisms of residual stress on workpiece surface are studied.By simulating geometry changes of worn tools,the influence of flank wear length on residual stress distribution of workpiece surface is studied,which provides a reference for optimizing actual milling process parameters.